2023:
Starter - ERA 4.73, OPS 783, WHIP 1.34, xFIP 4.02
Reliever - ERA 1.66, OPS 371, WHIP 0.69, xFIP 4.32
If you look at his Statcast, the big change is the value on his 4 seamer. There's no change in velo or hard hit rate (40ish%). Either he's been lucky while relieving, or the shorter starts have allowed him to control the pitch more effectively.